This research project is concerned with the factors regulating the secretion and function of thyrotrophin releasing hormone (TRH) and other related hypothalamic releasing hormones and neural peptides from the diffuse neuroendocrine system of vertebrate species, including man. The influence of physiologic stimuli, neurotransmitters, endocrine status and other factors on TRH secretion will be examined using a variety of in vivo and in vitro techniques. The functional implication of the anatomic and phylogenetic distribution of TRH, luteinizing hormone releasing hormone (LH-RH) and other hypophysiotrophic factors and neural peptides will be investigated. Experiments are being undertaken utilizing various chemical and immunologic techniques to characterize the nature of these neural peptides in neuronal and non-neuronal tissues of different species.